The present invention relates to liquid filtration. More particularly, the invention relates to a water pre-filter that utilized stored pressure to periodically back flush a sediment filter, removing any cleared detritus from the system through a drain port.
Water filtration often involves the use of multiple pre-filtration steps in order to remove sediment of gradually decreasing size. In practice, a large screen filter is first used to remove large objects from the water followed by filtration with screens of gradually decreasing mesh size. While it would be desirable to remove all of the sediment with a single filtering operation, use of a filter with small enough mesh size to clear the water in an initial step leads to rapid clogging of the filter screen by larger particles. As a result, water users have been forced to implement very expensive pre-filter systems in order to ensure uninterrupted water sources. It is therefore an overriding object of the present invention to provide a water pre-filter system wherein a fine mesh filter may be utilized in an initial filtering stage without the problems of clogging that have plagued previous designs.
In accordance with the foregoing objects, the present inventionxe2x80x94a self-cleaning pre-filter systemxe2x80x94generally comprises a system inlet; a sediment filter having a filter inlet in selective fluid communication with the system inlet, a selectively openable drain port and a filter outlet, separated from the filter inlet and the drain port by a filter screen; a pressure accumulator having a first chamber in open fluid communication with the filter outlet and having a sealed second chamber containing a compressible medium, the first chamber and the second chamber being separated one from the other by a flexible diaphragm; and a system outlet in selective fluid communication with the filter outlet and the first chamber.
In order to provide the desired selective fluid communications and the selective state of the drain port, the preferred embodiment of the present invention comprises an inlet valve between the system inlet and the filter inlet; a drain valve in the drain port; and an outlet valve between the first chamber and the system outlet. Preferably, each valve comprises a solenoid operated flow control valve, which may each be controlled by a provided system controller. In order to ensure maximum operational efficiency, the drain valve is also preferably a high capacity flow control valve relative to the inlet valve and the outlet valve. While the controller may comprise a dedicated state machine or micro-controller, those of ordinary skill in the art will recognize that the control function may also be integrated within the controller of a related device.
In operation, the controller operates the valves to periodically back flush the sediment filter utilizing energy stored in the pressure accumulator. Any detritus removed from the filter screen during the back flush process is immediately discharged from the system through the drain port. The controller then returns to the filter system to normal operation.
Finally, many other features, objects and advantages of the present invention will be apparent to those of ordinary skill in the relevant arts, especially in light of the foregoing discussions and the following drawings, exemplary detailed description and appended claims.